Arnold, C., & Sengonca, C. 2001 [Use of the fluorescent vital dye Acridinorange as an internal marker to investigate the exact larval stage of parasitation of Pulvinaria regalis Canard (Hom., Coccidae) by two parasitic wasps].. Mitteilungen der Deutschen Gesellschaft fur allgemeine und angewandte Entomologie 13(1-6): 121-124.

Notes: [Original title: Ermittlung des exakten Parasitierungsstadiums von Nymphen der Wolligen Napfschildlaus Pulvinaria regalis Canard (Hom.; Coccidae) durch Schlupfwespenarten mit Hilfe des internen Markierungsfarbstoffes Acridinorange.] In the present paper the fluorescent vital dye Acridinorange was used to investigate the correlation between scale size and parasitization of the parasitic wasps Coccophagus lycimnia and C. semicircularis. Therefore, one- to three-day-old adult wasps were fed with diluted solutions of honey water and the internal dye Acridinorange with a concentration ranging from 0.00001 to 1%. P. regalis-nymphs of different developmental stages and sizes were exposed to 15 of these female wasps for 24 hours, giving them the opportunity to lay eggs. Afterwards, the scales were removed from their host plants, measured and scanned for parasitization, using a fluorescent microscope. Additionally five adult females for each dye concentration were dissected and examined for labelling of different body tissues. The minimum scale size necessary for parasitization by the two wasp species was 0.92 mm for C. lycimnia and 0.98 mm for C. semicircularis, respectively. The anal plates measured 0.064 mm and 0.070 mm. A body size of 1.78 mm for C. lycimnia and 1.96 mm for C. semicircularis was needed when a second egg should be deposited within the scales. More than two eggs were laid in scales only when their size exceeded 2.35 mm and 2.47 mm, respectively. A combination of the obtained results with the knowledge about actual developmental stage and size of the scales led to a recalibration of the releasing time of the two parasitic wasps.